Aldehydes are important chemicals in the food industry. They serve as natural flavor additives to many food products. A preference among consumers for natural flavors exists as people are becoming more conscientious about their health and diet. Acetaldehyde is especially utilized by the food manufacturers as it provides a fresh flavor to many and various food products such as meats and breads. Acetaldehyde is important also for the synthesis of other desired products such as acetic acid and butanol.
Several methanol-utilizing microorganisms are capable of producing alcohol oxidase. This alcohol oxidase can then be used in the process of oxidizing alcohols such as ethanol into aldehydes such as acetaldehyde.
U.S. Pat. No. 4,481,292 was issued for the production of acetaldehyde from ethanol using an enzyme complex containing alcohol dehydrogenase, NADH, flavin mononucleotide, and a catalase. The U.S. Pat. No. '292 process requires intricate steps of purification, separation and removal of components of the enzyme complex and products. This requires increased operational complexity and increased time, thus reducing the economic feasibility.
U.S Pat. No. 4,920,055 was issued for the production of an aldehyde and hydrogen peroxide from alcohols having five or fewer carbon atoms, utilizing a methanol oxidase produced by Hansenula polymorpha. The U.S. Pat. No. '055 process uses a cell extract which is costly and results in yield loss. All examples in the U.S. Pat. No. '055 utilize purified enzymes. The process of purification reduces the economic feasibility of the process, as it takes time and money to purify the extract. Another disadvantage of the U.S. Pat. No. '055 process is that the enzyme is maintained in the system by either immobilization or recycling by use of membranes. Maintenance of the sufficient enzyme activity tends to be difficult by such immobilization and/or recycling.